字符集和校验规则
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MySQL字符集
在MySQL中，字符集（Character Set）用于定义存储和处理文本数据的字符编码规则。字符集决定了 MySQL 如何解释和处理不同字符的存储和比较操作。它对于确保数据的正确性、一致性和可移植性非常重要。
在创建数据库时，如果不指定字符集和校验规则，那么 MySQL 会帮我们自动选择默认的字符集和校验规则。
查看默认的字符集。
SHOW variables LIKE 'character_set_database';
+------------------------+---------+
| Variable_name | Value |
+------------------------+---------+
| character_set_database | utf8mb4 |
+------------------------+---------+
查看默认的校验规则。
SHOW variables LIKE 'collation_database';
+--------------------+--------------------+
| Variable_name | Value |
+--------------------+--------------------+
| collation_database | utf8mb4_0900_ai_ci |
+--------------------+--------------------+
查看当前支持的所有字符集。
SHOW charset;
查看当前支持的所有校验规则。
SHOW collation;
MySQL8.0支持的所有字符集
+----------+---------------------------------+---------------------+--------+
| Charset | Description | Default collation | Maxlen |
+----------+---------------------------------+---------------------+--------+
| armscii8 | ARMSCII-8 Armenian | armscii8_general_ci | 1 |
| ascii | US ASCII | ascii_general_ci | 1 |
| big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 |
| binary | Binary pseudo charset | binary | 1 |
| cp1250 | Windows Central European | cp1250_general_ci | 1 |
| cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
| cp1256 | Windows Arabic | cp1256_general_ci | 1 |
| cp1257 | Windows Baltic | cp1257_general_ci | 1 |
| cp850 | DOS West European | cp850_general_ci | 1 |
| cp852 | DOS Central European | cp852_general_ci | 1 |
| cp866 | DOS Russian | cp866_general_ci | 1 |
| cp932 | SJIS for Windows Japanese | cp932_japanese_ci | 2 |
| dec8 | DEC West European | dec8_swedish_ci | 1 |
| eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci | 3 |
| euckr | EUC-KR Korean | euckr_korean_ci | 2 |
| gb18030 | China National Standard GB18030 | gb18030_chinese_ci | 4 |
| gb2312 | GB2312 Simplified Chinese | gb2312_chinese_ci | 2 |
| gbk | GBK Simplified Chinese | gbk_chinese_ci | 2 |
| geostd8 | GEOSTD8 Georgian | geostd8_general_ci | 1 |
| greek | ISO 8859-7 Greek | greek_general_ci | 1 |
| hebrew | ISO 8859-8 Hebrew | hebrew_general_ci | 1 |
| hp8 | HP West European | hp8_english_ci | 1 |
| keybcs2 | DOS Kamenicky Czech-Slovak | keybcs2_general_ci | 1 |
| koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 |
| koi8u | KOI8-U Ukrainian | koi8u_general_ci | 1 |
| latin1 | cp1252 West European | latin1_swedish_ci | 1 |
| latin2 | ISO 8859-2 Central European | latin2_general_ci | 1 |
| latin5 | ISO 8859-9 Turkish | latin5_turkish_ci | 1 |
| latin7 | ISO 8859-13 Baltic | latin7_general_ci | 1 |
| macce | Mac Central European | macce_general_ci | 1 |
| macroman | Mac West European | macroman_general_ci | 1 |
| sjis | Shift-JIS Japanese | sjis_japanese_ci | 2 |
| swe7 | 7bit Swedish | swe7_swedish_ci | 1 |
| tis620 | TIS620 Thai | tis620_thai_ci | 1 |
| ucs2 | UCS-2 Unicode | ucs2_general_ci | 2 |
| ujis | EUC-JP Japanese | ujis_japanese_ci | 3 |
| utf16 | UTF-16 Unicode | utf16_general_ci | 4 |
| utf16le | UTF-16LE Unicode | utf16le_general_ci | 4 |
| utf32 | UTF-32 Unicode | utf32_general_ci | 4 |
| utf8mb3 | UTF-8 Unicode | utf8mb3_general_ci | 3 |
| utf8mb4 | UTF-8 Unicode | utf8mb4_0900_ai_ci | 4 |
+----------+---------------------------------+---------------------+--------+
指定字符集和校验规则
创建一个名为 mydb 的数据库，字符集为 gbk，校验规则为 gbk_chinese_ci。
CREATE DATABASE mydb DEFAULT CHARACTER SET gbk COLLATE gbk_chinese_ci;
这里的 DEFAULT CHARACTER SET 也可以简写为 CHARSET。
CREATE DATABASE mydb CHARSET gbk COLLATE gbk_chinese_ci;
查看创建结果。
SHOW CREATE DATABASE mydb\G
*************************** 1. row ***************************
Database: mydb
Create Database: CREATE DATABASE `mydb` /*!40100 DEFAULT CHARACTER SET gbk */ /*!80016 DEFAULT ENCRYPTION='N' */